Water treatment system and method

ABSTRACT

A method of handling grey water and optionally at least a portion of black water for disposal from vehicles such as boats, recreational vehicles or rural dwellings such as cottages, camps and the like, not having direct access to sewer systems, involves the treatment of such waste water with ozone. A batch system is used whereby a predetermined quantity of water to be treated is captured in a treatment tank. A circulating pump withdraws water from the tank and pushes the water along a treatment conduit, the conduit containing an ozone/water mixer and returns the water to the treatment tank. The treatment conduit has a discharge valve that is maintained in a closed position for a selected period of time. Ozone is fed to the ozone/water mixer from an ozone generator which is advantageously fitted with an air pump to pressurize the feed gas. After the selected treatment time, the batch is discharged to a drain through the discharge valve. Advantageously, the ozone generator can also be used to “polish” raw water from a lake or stream to enhance its usability on board a vessel or in a rural dwelling.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit from U.S. Provisional Application Ser.No. 60/125,782 filed Mar. 23, 1999 which is incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

The invention relates to a method and apparatus for the treatment ofwater. The water treatment method and apparatus may be applied to fluidssuch as grey or black water to be treated prior to discharge or rawwater to be treated prior to consumption.

BACKGROUND OF THE INVENTION

In the field of grey/black water disinfection, great efforts arecontinuously being made to reduce the quantity and concentration ofpollutants found in grey/black water being discharged into rivers,lakes, surface and ground water supplies, etc. This is evidenced by moreand stricter government regulations and requirements relating togrey/black water treatment processes and discharges. The quantities ofhuman wastes requiring treatment are constantly and rapidly increasing.In the field of potable water purification, available surface and groundwater sources are rapidly deteriorating due to pollution caused bycontaminates generated by a growing population and their careless use ofwater and improper disposal of waste products.

Many methods exist for the treatment of grey/black water. Biological orchemical disinfection of the grey/black water to neutralize the harmfulmicro organisms within grey/black water are common methods employed toreduce bacteria loading found in grey/black water. Biologicaldisinfection of grey/black water requires large tanks for microorganisms to consume the biological waste contained within thegrey/black water. Chemical disinfection of grey/black water is notacceptable for water based communities and activities.

Many methods also exist for the purification of potable water whichinclude the use of chemical disinfectants, microfiltration andultra-violet radiation. The most commonly used disinfectant is chlorineand when water containing organic material and compounds is chlorinated,a range of carcinogenic trihalomethanes is generated and considerablecontact time is required for effective disinfection. Whenmicrofiltration is used to remove biological contaminants, the filteringdevices require constant and regular servicing. When ultra-violetradiation is used to make water potable, the effectiveness is limited bythe clarity of the water being treated. These physical and chemicalfactors place severe limitations on these methods of disinfection inrecreation facilities.

SUMMARY OF THE INVENTION

In accordance with the invention, there is a system for treating waterfor disposal. The system comprises a treatment tank, a treatmentconduit, a water circulating pump, ozone generating means, ozone watermixing means, a discharge valve and control means. The control means areadapted to control cycling of the water circulation pump. The controlmeans also control generation of ozone by the ozone generator. Thecontrol means further control the position of the discharge valve. Thetreatment tank includes water level sensing means to determine thepresence of a fixed quantity of water in the treatment tank. The controlmeans comprise timing means for operating the water circulation pump fora selectable time period.

In accordance with the invention, a method for treating water prior todisposal comprises the steps of collecting a predetermined quantity ofwater to be treated in a treatment tank and thereafter mixing with thepredetermined quantity of water to be treated, ozone. The selectedquantity of water to be treated is mixed with the ozone for a selectedperiod of time. Thereafter the mixed water is discharged to waste.

In another aspect of the invention, the output of the ozone generatormay also be directed to a water intake system. Lake water drawn into thewater intake system is mixed with ozone from the ozone generator totreat the raw water to enhance the quality of the raw water for drinkingpurposes. The treated water may also be filtered to further enhance thepotability of the water.

BRIEF DESCRIPTION OF THE FIGURES

The invention will now be discussed in association with the followingdrawings, which illustrate preferred embodiments of the invention.

FIG. 1 illustrates a system embodying a first aspect of the invention;

FIG. 2 illustrates a system embodying an alternate aspect of theinvention;

FIG. 3 illustrates an alternative embodiment of a portion of the systemof FIG. 1;

FIG. 4A illustrates a first arrangement of parts of a portion the systemof FIG. 1, and

FIG. 4B illustrates an alternate arrangement of the parts of the portionof the system of FIG. 1 illustrated in FIG. 4A.

The term “grey water” is used in this description and in the claims todescribe water which is not human sewage but results from use by humanssuch as in washing and the like. The term “grey water” can encompasseffluent from sinks, showers and the like. The term “black water” isused in this description and claims to refer to water in which humansewage is a significant component. Black water normally results fromeffluent from toilets and the like.

The term “potable water” is used in this description and claims to referto water which is fit for human consumption.

The term “raw water” is used in this disclosure and claims to refer toambient liquid such as may be found in surface water comprising lakes,rivers, streams and the like, and in addition, ground water such as maybe contained in wells, whether dug or drilled, as well as run off watersuch as collected rain water and the like. The term “raw water” isintended to cover all liquids other than water which is primarily eithergrey water or black water.

The term “disinfection” as used in this disclosure and the claims,refers to treatment of water to reduce the harmful bacteria content ofthe water. In the case of use of the term “disinfection” with grey wateror black water, the term is intended to encompass reducing the bacteriacontent of the water to a level acceptable for discharge to the intendedenvironment, whether that be on land or into other surface water. Inconnection with the term potable water, the term “disinfection” isintended to encompass reducing the bacterial content of raw water to thestate that the water, after treatment, is suitable for human drinkingconsumption.

The embodiment of the water treatment system illustrated in FIG. 1 isillustrated generally at 10. The principal components of the systeminclude a treatment tank 20, a solenoid controlled discharge valve 30, acontroller 80, and an ozone generator 40. Preferably, the systemincludes a grey water collection tank 60. Optionally, the system mayalso include a black water collection tank 70.

The water treatment system 10 includes a treatment conduit 22 comprisingwithdrawal conduit 24 and a return conduit 26, a circulating pump 28,and a treatment mixer 42. The system 10 further comprises a supplyconduit 44 and a vent conduit 46. The system 10 also includes adischarge conduit 32, and an air inlet 41.

The valve 30 includes a solenoid for controlling the position of thevalve 30.

The grey water collection tank 60 includes an inlet 62, a transfer pump64 and a transfer conduit 66 which advantageously includes a check valve68.

The embodiment illustrated in FIG. 1 is particularly adapted for use invehicles having relatively reduced space for collection of grey waterand advantageously black water. Such vehicles may include recreationvehicles, water vessels and the like. It should be understood, however,that while the invention is discussed in association with itsapplication to a marine vessel, the system is equally applicable to usein land based mobile vehicles such as recreational vehicles and the likeand also to fixed installations such as in buildings not havingconnection access to sewage treatment systems such as rural properties,cottages and the like.

Grey water is collected by suitable piping from all sinks, showers,washing facilities and the like and directed to the grey water inlet 62.Grey water continues to enter the collection tank 60. The transfer pump64 may be located in the bottom of the grey water collection tank 60 andmay be operated by means of a float switch or the like. Upon operationof the transfer pump 64, grey water collected in the collection tank 60is transferred via the transfer conduit 66 through the check valve 68 tothe treatment tank 20. The transfer pump 64 will operate until such timeas a determined quantity of grey water fluid is contained within thetreatment tank 20. The treatment tank 20 includes a high level sensor 82which may be a float which is connected to the controller 80 by inputline 84. The volume of the treatment tank 20 as determined by high levelsensor 82 defines a selected volume Q₁ of grey water to be treated.

When the high level sensor 82 senses that the volume Q₁ of the greywater is in the treatment tank 20, the controller 80 shuts off thetransfer pump 64 via line 86 to ensure that no additional grey water isadded to the treatment tank 20. As a further option, the transferconduit 66 may include a solenoid controlled valve 69 controlled bycontroller 80 through line 88 to ensure no gravity flow from collectiontank 60 to treatment tank 20.

Once the treatment tank 20 has been filled with quantity Q₁, thecontroller will cycle the circulating pump 28 which is connected to thecontroller by line 90. Upon operation of the circulating pump 28, liquidwill be circulated through the treatment conduit 22. Liquid will bewithdrawn through withdrawal conduit 24 to the pump 28 by valve 30 andthrough return conduit 26 to the tank 20. The valve 30 is positioned atall times during treatment to direct flow from the withdrawal conduit 24into the return conduit 26 and prevent flow through the dischargeconduit 32 until opened by controller 80.

The ozone generator 40 is a commercially available ozone generator. Aparticularly suitable equipment for a marine application is the ozonegenerator sold by A. H. Simpson Industries Limited of Ontario, Canada,under the model designation SW400. The ozone generator 40 draws inambient air through the inlet 41. To enhance efficiency of the ozonegenerator, the inlet 41 advantageously directs the ambient air through adryer 43. The air is then fed to the ozone generator 40 so that ozone isgenerated. The ozone generated then passes along the supply conduit 44to the inlet point of a treatment mixer 42 located in the return conduit26. Preferably the treatment mixer is a venturi injector. A suitableventuri injector is the equipment sold by Mazzei Injector Corporation ofCalif., U.S.A., under the model designation 384. The controller 80 turnson the ozone generator 40, which is connected by line 92, when thecirculating pump 28 is cycled.

Under the effect of the circulating pump 28, liquid to be treated iscontinuously withdrawn from the treatment tank 20, circulated throughthe withdrawal conduit 24 where it passes by the valve 30 and into thereturn conduit 26. The passage of the liquid by the treatment mixer 42draws ozone into the liquid to be treated thereby ensuring delivery ofozone to the fluid circulating in the treatment conduit and ensuringintimate mixing of ozone with the liquid travelling along the treatmentconduit.

The treatment of grey water is essentially a batch system. The volume ofwater to be treated is determined by the volume of the treatment tank20. The designated volume of water to be treated, Q_(1,) is thuscirculated by the circulating pump 28 continuously by the treatmentmixer 42. The circulating pump 28 and the ozone generator 40 operate fora predetermined period of time T₁ to ensure that a suitable supply ofozone is injected into the liquid to be treated and to provide suitablecontact between the ozone and all of the liquid to be treated.

After a designated period of time, T₁ of operation of the circulatingpump 28, the controller 80 moves valve 30 to the discharge connectposition by means of control line 94. At this time, the circulating pump28 then withdraws liquid from the treatment tank 20 and discharges thatliquid through the discharge conduit 32. The circulating pump 28continues to run until the treatment tank 20 is emptied. Emptying of thetreatment tank 20 is sensed by a low level sensor 96. A signal is passedthrough line 98 to controller 80. The controller then stops the pump 28and the generator 40 and resets all controlled items ready to handleanother batch.

Since this is a batch process, the amount of liquid Q₁ to be treated isknown. The treatment time T₁ can also be set by the controller to ensuretreatment for any desired length of time. The amount of ozone generatedby the ozone generator 40 in time T₁ will also be known. As during thetreatment, ozone is admixed continuously into the liquid being treatedby the mixer 42, sufficient contact time can be ensured to ensuretreatment of the quantity Q₁ of grey water to any desired level. Thevolume of the treatment tank 20 can be configured to meet whateverconstraints drive the overall size of the equipment. Where the equipmentis to be installed on a marine vessel, space may be at a premium and thebatches treated may be relatively small batches in the order of 3gallons. With a small volume of Q₁, the treatment time T₁ may berelatively short, in the order of 3 minutes. Where space is not quitesuch a premium, then the treatment tank may be larger; with a largertreatment volume Q₁, longer circulation times T₁ can be programmed intothe controller to ensure satisfactory contact of the batch with theozone to provide suitable treatment prior to discharge. One of theadvantages of providing the optional collection tank 60 is the provisionof additional storage of grey water prior to treatment . Thus, if ashower is being used, the grey water from the drain may be collected atany convenient flow rate which is not subject to the batch treatmentlimitation, Q₁ and T₁. The size of the grey water collection tank willbe determined by desired interim storage capacity and the treatmentparameters of time and quantity.

In circumstances such as marine vessels and the like there will still berequired, holding tanks for black water. Black water emanating from thevessel's toilet will need to be collected in a black water collectiontank 70. As the primary constituent of such black water will be humansewage, this will normally be stored in the tank and subsequently pumpedout in available pump out stations. However, in order to extend thecapacity of the black water holding tank 70, the black water holdingtank may be arranged so that an overflow conduit 72 may be arranged topermit liquid above a certain level in the black water holding tank 70to flow over by gravity into the grey water collection tank 60. Liquidsat the top of the black water collection tank 70 may be, in essence, notsubstantially different than the content of the grey water input andthus may be suitable for treatment in the batch system discussed above.Sediment or other nonliquid constituents of the black water holding tank70 would, however, be retained in the lower reaches of the black waterholding tank where they will remain until pumped out at a sanitary pumpout station. By providing an over flow of the black water holding tank70 for the liquids at the upper reaches of the black water holding tank,the effective capacity of the vessel between required pump outs may beextended by treating the upper surface liquids in the grey watertreatment system.

Advantageously the treatment system 10 also comprises an ozone ventconduit 46. The vent conduit 46 communicates from the top of thetreatment tank 20, ultimately to the discharge conduit 32. As ozone iscontinuously introduced into the batch during the operation of thecirculating pump 28, gas pressure may build up in the treatment tank 20.Any ozone building up in the treatment tank 20 is then vented to thedischarge conduit 32 ensuring that a continuous fresh supply of ozonefrom the generator 40 will be introduced into liquid being treatedthrough the treatment mixer 42. Advantageously, the ozone conduit vent46 may be directed to the grey water collection tank 60. Thus, any ozonefrom conduit line 46 will achieve slight pretreatment and deodorizationin the collection tank 60. The collection tank 60 is vented in turnthrough conduit 46A to the discharge conduit 32. Check valves 47A and47B ensure no back flow in vent conduit 46 and 46A respectively. Also,as shown diagrammatically, the vent conduit 46A contains a verticallyupwardly directed run 48 to prevent inadvertent draining of collectiontank 60 directly to discharge conduit 32 which might occur while avessel is moving through wave action or other motion.

FIG. 2 illustrates a modified version of the treatment system shown inFIG. 1. The treatment system in FIG. 2 is essentially similar to thetreatment system shown in FIG. 1 with the addition of a potable watertreatment system utilizing the same ozone generator. Similar parts ofthe system 110 shown in FIG. 2 corresponding to those in FIG. 1 havebeen given like numbers with the prescript 1. Thus, ozone generator 140in FIG. 2 corresponds to ozone generator 40 in FIG. 1.

Accordingly, the water treatment system 110 as shown in FIG. 2 comprisesa grey water collection tank 160, treatment tank 120 and ozone generator140. The circulating pump 128 circulates liquid to be treated throughthe withdrawal conduit 124 and through return conduit 126. The returnconduit 126 includes a treatment mixer 142. After treatment for the settime the valve 130 in the treatment conduit 122 is opened by controller180 so that the circulating pump 128 discharges through the dischargeconduit 132. Advantageously a black water collection tank 170 is fluidlyconnected to the collection tank 160 by an overflow conduit 172. Thetransfer pump 164 transfers liquid from the collection tank 160 throughthe transfer conduit 166 by check valve 168, into the treatment tank120.

The system 110 includes a potable water treatment system illustratedgenerally at 175. In the system 110 illustrated in FIG. 2, the supplyconduit 144 comprises a second conduit 144A for delivery of ozone fromthe ozone generator to the potable water system 175.

The potable water treatment system comprises a raw water inlet system177, check valve 179, a filter 181, a supply pump 183, a supply mixer185, a retention and air release tank 187 and a carbon black filter 189.The supply mixer 185 may be similar to treatment mixer 142 and treatmentmixer 42. The potable water treatment system 175 comprises a potablewater outlet 191 which may be connected to taps, tanks or other desiredsources of drinking water within the facility in which the system 110 isinstalled.

The potable water purification system 175 commences to operate uponoperation of the supply pump 183. The supply pump 183 may be cycled bydemand such as with a manually operated switch such as a foot switch orthe like. When the supply pump 183 operates the controller receives asignal through line 193 and the ozone generator 140 is also turned on tosupply ozone. Raw water from ambient such as a lake, river, or stream,in the case of a boat, or a well or other suitable surface water at acottage or rural dwelling, is drawn through the raw water inlet 177. Thecheck valve 179 prevents any back flow. The raw water is first passedthrough a filter 181 to remove any gross particles in the water prior toentry into the supply pump. The supply pump 183 then forces the water tobe treated through the supply mixer 185. The supply mixer draws theozone from the generator 140 and ensures mixing and contact with the rawwater. The tank 187 provides a facility for releasing any gases or ozonecontained in the water for collection in the tank 187. A final“polishing” of the water is achieved by passing the water through thecarbon black filter 189. In addition, the carbon black filter 189converts any ozone molecules in the raw water to oxygen molecules. Afterpassage through the filter 189 the water is delivered to the source ofdrinking water.

The system 110 provides a very compact system for use in vehicles wherestorage capacity is limited. As all incoming raw water is treated, theneed to maintain large fresh water storage tanks on a vessel can besubstantially reduced, if not totally eliminated. The amount of holdingtank capacity for black water may be reduced and the opportunity fortreatment of all grey water before overboard discharge will eliminatethe need for substantial grey water holding capacity.

As set out above, the size of the batch of material to be treated, Q₁,can be determined by the designer of such a system based on availablespace requirements. The treatment time T₁ is advantageously selected toensure appropriate treatment of the waste water to meet applicabledischarge regulations. The treatment need of grey water is oftenspecified in terms of biological oxygen demand (BOD) and chemical oxygendemand (COD). Grey water will be wide ranging from waste water which hasa very low BOD and low COD to waste water having a much higher BOD and amuch higher COD. There are two additional factors which areadvantageously considered when determining the treatment time T₁. Theseinclude the amount of ozone that is available for mixing with the waterbeing circulated by the circulating pump 28 and also the success indissolving the available ozone in the water. The contacting of theavailable ozone with the water occurs initially in the treatment mixer42, but of course continues in the turbulence which occurs as the wateris circulated through the treatment conduit 22, the pump 28 and thetreatment tank 20. We have carried out tests for these features todetermine preferred operating conditions of the system.

A first group of tests were carried out using dechloronized, deionizedand filtered laboratory water as the water to be treated. This lowdemand test water has essentially no BOD nor COD. This low demand testwater was then used in tests to determine the effectiveness of ozoneinjection and dissolving of the ozone in the water. The effectivenesswas determined by measuring the residual ozone in the low demand waterusing a spectrometer. For these tests, a ozone generator available fromA. H. Simpson as outlined above was used in the test system togetherwith different sizes and numbers of injectors from Mazzei Injector Corp.

Surprisingly, the first batch of tests showed an unsatisfactory residualozone created in the low demand water. Observed ozone levels generallywere less than 0.5 mg/liter of low demand water.

Various steps were taken to attempt to increase the residual ozoneamount. As one test, the air inlet 41 was equipped with a supply ofcommercial oxygen. Using commercial oxygen produced increased residualozone in the water circulating in the treatment conduit 22. Also, asmight be expected, increasing the processing time T also tended toincrease the residual ozone in the water.

As an additional part of this testing program, a high demand (high BODand COD) test fluid was created in the laboratory. Because of the highdemand, it was felt that such tests would be a useful indicator todetermine whether the required amount of ozone necessary to treat greywater or contaminated water was in fact available and dissolved in thewater. The tests were carried out using commercial oxygen supplied tothe inlet 41. After running the system for times slightly less andslightly greater than 2 minutes, it was determined that the residualozone in the high demand water being treated was either zero or onlyslightly above zero. This lack of residual ozone appears to indicatethat all available ozone was consumed by the BOD and COD demand of thewater and from this it may be inferred that insufficient treatment mayhave occurred.

In order to overcome the apparent limitations as set out in these firstexperiments, various techniques were tested. As stated above, providinga commercial oxygen supply rather than using ambient air, initiallyprovides greater oxygen to the generator, thus resulting in moreconversion to ozone and a greater quantity of ozone is available insupply conduit 44.

Another aspect of solution of these observations was to obtain bettermixing of the available ozone. While a single ozone injector isdescribed and illustrated in FIG. 1 and labelled treatment mixer 42, useof a plurality of injectors assists in both the flow of ozone into thetreatment liquid and additionally mixing of the available ozone into thewater to be treated. Thus, tests were carried out using a plurality ofinjectors operating in parallel to see if this would show increasedlevels of residual ozone in low demand water. Finally, consideration wasgiven to using two circulating pumps in place of the single circulatingpump 28 illustrated in FIG. 1, to provide enhanced circulation. Usingpumps operating in parallel, a higher volume of flow of water throughthe treatment conduit 22 would be achieved. This, in turn, would producehigher vacuum in the treatment mixer or mixers, thus drawing more ozoneinto the system as well as assisting in mixing the ozone generated withthe water being treated.

In subsequent testing, another avenue wag explored in an effort toensure suitable treatment. This included the use of larger ozonegenerators. Firstly, tests were done using a generator produced by theA. H. Simpson company which was rated as being capable of generating 400mg of ozone per hour. A still larger A. H. Simpson generator capable ofproducing 800 mg of ozone per hour was then used. This step helped toincrease the residual oxygen in the low demand water, but at increasedcost for the larger ozone generator.

Tests which had been conducted were conducted using atmospheric airavailable in the laboratory where the tests were being carried out, or asupply of commercial oxygen available in the laboratory was used forinput to inlet 41. As beneficially increased results were occurringusing commercial oxygen as the source of gas entering inlet 41, avenueswere then explored to determine whether there was sufficient oxygenavailable in the gas being drawn into the inlet 41. As an experiment onthis point, additional ducting was added to the inlet 41 so as to drawin outside air rather than indoor air available in the laboratory. Thisalso gave increased residual ozone in the low demand water being tested.The outside air being drawn in had a higher relative humidity. This thenshowed that use of a dryer such as dryer 43 in inlet 41 gave much betterproduction of ozone from the generator. Thus, in preferred embodiments,particularly when moisture laden air is drawn in to inlet 41, a dryer isadvantagously used.

As an additional step in enhancing the effectiveness of dissolution ofthe ozone generated, into the water being circulated, a surfactant wasadded to the low demand water. The use of a surfactant, when other testconditions remained the same, increased the residual ozone in the waterbeing circulated. This indicates that the surfactant aids in the uptakeof the ozone so that there is in fact a higher residual ozone content ofthe mixed water, thereby leading to enhanced treatment. The surfactantadded more closely mimics grey water which will naturally containsurfactants in the form of detergents or other soaps, in most cases.

A test was then carried out on a laboratory created simulated highlycontaminated water. The system as shown in FIG. 1, was operated using aSimpson ozone generator rated as being capable of producing 800 mg/hourof ozone. Three Number 3, Mazzei injectors operating in parallel wereused. The Simpson ozone generator was supplied with pure oxygenavailable in the laboratory. The batch size was 10.9 liters or 2.40imperial gallons. The system was operated for a processing time of justover 50 seconds with low demand water. First, the residual ozone in lowdemand water was measured at slightly over 1.5 mg/liter. A test was thenrun on this sytem with a simulated highly contaminated water. The watertreated was generated in the laboratory to simulate water having a veryhigh BOD and a very high COD typical of the highest levels of demandnormally experienced when dealing with grey water and to make the testmore severe, the test sample additionally contained a concentratedsewage from a sewage collection facility.

This highly contaminated water was then used to determine the percentagereduction which might be achieved in respect of the Total Coliform,Fecal Coliform and E-coli using the system described above. The amountof Total Coliform, Fecal Coliform and E-coli was analyzed beforetreatment and after treatment and the figures compared. Although severe,it is considered that this is an apt test to demonstrate theeffectiveness of the system. The ozone introduced into the highlycontaminated water will first be used up in satisfying the BOD and theCOD. Any ozone remaining after satisfying these demands is thenavailable to kill any bacteria, viruses, parasites and spors which maybe present in the water to be treated. By determining the reduction inTotal Coliform, Fecal Coliform and E-coli, a useful measure of theeffectiveness of the system is obtained.

The system was operated for 25 seconds in a first test, 53 seconds in asecond test and 95 seconds in the third test on this highly contaminatedwater. When run for 25 seconds, the analysis of the treated fluid showedthat E-coli had been reduced by 18%, Total Coliform did not show anysignificant reduction and Fecal Coliform had been reduced by 10%. Thisresult shows insufficient treatment of the water. When the system wasrun for 53 seconds, the treated water showed that E-coli had beenreduced 35%, Total Coliform count had been reduced by 37% and FecalColiforms had been reduced by 67%. This shows improved results, but thislevel is still likely to be insufficient to meet most dischargerequirements.

When the system was operated for 95 seconds, analysis of the treatedwater showed that E-coli had been reduced by 99.40%, Total Coliform hadbeen reduced by 99.67% and Fecal Coliform had been reduced by 94.60%.This is an excellent result.

The results of these tests do show, as indicated above, that the time oftreatment T₁ is a significant factor in producing a satisfactorytreatment level. The test using the system operating as explained abovefor a time of 95 seconds shows excellent treatment of the highlycontaminated water, a result which would permit overboard discharge froma marine vessel in accordance with most disposal regulations. Such asystem is thus able to treat a batch of approximately 10.9 liters ofhighly contaminated water in just over one and a half minutes.

As the system described above in connection with these tests has beendemonstrated to operate successfully, further tests were then carriedout to optimize the system components. Tests were performed utilizing aseries of larger generators from the A. H. Simpson company. While thesetests indicate slightly increased residual ozone in low demand water,the increase in available ozone did not appear to offset the increasedcost of providing a larger generator. Surprisingly, during these tests,it was ascertained that a factor in the amount of ozone produced arisesfrom the fact that the ozone system as explained above was notpressurized. Ozone is supplied in the treatment conduit as outlined inFIG. 1 by reason of the negative pressure developed by the treatmentmixer 42. The treatment mixer 42, being of the venturi type, produces asuction pressure which draws the ozone into the treatment mixer. Anadvantageous modification of the structure illustrated in FIG. 1 isillustrated in FIG. 3. The inlet 41 for the ozone generator 40 includesa dryer 43 and an air pump 45. The air pump 45 thus pressurizes the feedto the ozone generator 40. Using pressurized air, satisfactory residualozone was produced in the fluid to be treated when determined by using asample fluid having little or no BOD and COD. Pumping air into the ozonegenerator gives successful results using fresh ambient air so thatcommercial oxygen which otherwise would increase cost of operation isnot required.

Another surprising aspect that developed during such testing, is therole played by the arrangement of the batch treatment tank. FIGS. 4A and4B show diagrammatically, two different arrangements of the batchtreatment tank. In FIG. 4A, the return conduit 26 enters the treatmenttank 20 at the upper regions of the tank substantially adjacent to thehigh level sensor 82. In FIG. 4B, the return conduit 26 enters thetreatment tank 20 substantially below the level of the fluid in the tankadjacent to the low level sensor 96. With the arrangement of the returnconduit 26 adjacent the upper region of the treatment tank as shown inFIG. 4A, it was noted that additional flow of gas was achieved in supplyconduit 44. With the return conduit 26 located adjacent the lower regionof the treatment tank as shown in FIG. 4B, there was less flow in thesupply conduit 44. However, the flow of greater amounts of ozone insupply conduit 44 with the configuration of FIG. 4A did not lead toincreased residual ozone in the water to be treated. In fact, thegreatest residual ozone level was achieved with the arrangement shown inFIG. 4B. Operating the device as illustrated in FIG. 4A usingatmospheric air rather than pressurized air to the inlet 41 showed anincreased flow in supply conduit 44 of 4.75 cubic feet per hour, but aresidual ozone in the low demand water of only 0.23 mg/liter after 96seconds cycle time. Using the same equipment, but with a bottom feed tothe treatment tank 20 as illustrated in FIG. 4B, the flow rate in supplyconduit 44 was observed to have fallen to 3 cubic feet per hour.However, after the same processing time, the residual ozone in the lowdemand water had increased to 0.39 mg/liter. These figures appear toindicate that returning the water from the treatment mixer 42 to thebottom of the batch treatment tank 20 further assists in dissolving theozone into the water where it is available for treating the water.

Based on the above testing, a commercially effective arrangementinvolves the use of an air pump feeding a moderate sized ozone generatorsuch as the Simpson generator rated at 800 mg/hr production, with theair pump moving a supply of fresh air drawn in through a dryer. The useof larger ozone generators does not seem to be cost justified. OneMazzei No. 8 mixer also appeared to be sufficient although a No. 6injector may also be sufficient. Use of multiple parallel venturiinjectors did not produce results sufficiently enhanced to offset theexpense of the multiple injectors. Best results were achieved using abottom feed to the treatment tank 20.

From reviewing the above examples and description, it will beappreciated that a relatively compact system can be created forsuccessful treatment of highly contamined water having very high BOD andCOD and various pollutants to the point where the treated water issubstantially enhanced before being discharged. The effectiveness of thesystem in treating contaminated water also shows that the system may beused in a combined system, for enhancing the quality of drinking waterproduced from raw water which may be available from a lake or on boardthe vessel or facility where the system is installed.

Although municipal regulations may not yet permit the discharge of blackwater after treatment in such system, the above tests with highlycontaminated fluids show that even water having very high BOD and veryhigh COD and other pollutants can be treated in the system in accordancewith this invention. Such a system may be acceptable for treatment ofthe non-solids portion of black water or at least a portion of thecontents of a black water holding tank.

While the system has been described in connection with preferredembodiments of the system, various changes and modifications to thesystem may be made. The full scope of the invention is to be determinedby reference to the following claims.

We claim:
 1. A system for treating a predetermined quantity of wastewater for disposal, said system comprising a treatment tank, saidtreatment tank having a capacity sufficiently large to accommodate saidpredetermined quantity of water, a transfer conduit for transferringwater into said treatment tank, shut off means for preventing flowthrough said transfer conduit, a treatment conduit, a water circulatingpump located within said treatment conduit, an ozone generator, at leastone ozone/water mixer, a discharge valve, and control means, saidcontrol means controlling cycling of said water circulation pump, saidcontrol means controlling operation of said ozone generator, saidcontrol means controlling the position of said discharge valve, saidtreatment tank comprising water level sensing means to determine thepresence of said predetermined quantity of water in said treatment tank,said control means comprising timing means for operating said watercirculating pump for a selectable time period, said control meanscontrolling said shut off means to stop flow through said transferconduit when said water circulation pump is operating.
 2. The system ofclaim 1 wherein said system further comprises an air pump, said air pumpadapted to deliver gas under pressure to said ozone generator.
 3. Thesystem of claim 2 wherein said air pump is in an inlet for said ozonegenerator and said inlet is adapted to draw in air from ambientsurroundings.
 4. The system of claim 3 wherein said inlet includes adryer for drying said air.
 5. The system of claim 2 wherein said airpump is connected to a source of oxygen.
 6. The system of claim 1wherein said system comprises a treatment conduit and said watercirculating pump is located within said treatment conduit, and whereinsaid treatment conduit comprises an exit end for returning water fromsaid treatment conduit to said treatment tank.
 7. The system of claim 6wherein said exit from said treatment conduit is located on saidtreatment tank below the level of liquid in said treatment tank.
 8. Thesystem of claim 7 wherein said exit is adjacent the bottom of saidtreatment tank.
 9. The system of claim 7 wherein said treatment tankcomprises a high level sensor for sensing an upper level of liquidwithin said treatment tank, said high level sensor comprising an outputsignal for indicating that liquid level in said treatment tank hasreached a predetermined level.
 10. The system of claim 9 wherein saidsystem comprises a grey water collection tank, said transfer conduittransfers water from said grey water collection tank to said treatmenttank and wherein said transfer conduit comprises at least one valve, andwherein said control means closes said at least one valve in saidtransfer conduit upon receiving a signal from said high level sensormeans.
 11. The system of claim 10 wherein said system further comprisesa black water collection tank, said system further comprising a secondtransfer conduit for transferring liquid from said black watercollection tank to said grey water collection tank.
 12. The system ofclaim 10, said system further comprising potable water treatment means,said potable water treatment means comprising a raw water inlet, a rawwater circulation pump, an ozone mixer for mixing ozone with raw water,and a filter for removing dissolved ozone from said water after mixingwith said water.
 13. A system for treating a predetermined quantity ofwaste water for disposal, said system comprising a waste watercollection tank, a waste water treatment tank, a transfer conduit fortransferring water into said treatment tank, shut off means forpreventing flow through said transfer conduit, a treatment conduit, awater circulating pump, an ozone generator, at least one ozone/watermixer, a discharge valve and control means, said treatment conduitincluding said water circulating pump and said at least one ozone/watermixer and wherein said discharge valve is in fluid communication withsaid treatment conduit, said control means, controlling cycling of saidwater circulation pump, said control means controlling operation of saidozone generator, and said control means controlling the position of saiddischarge valve, said waste water treatment tank including water levelsensing means to determine the presence of said predetermined quantityof water in said treatment tank, said control means comprising timingmeans for operating said water circulating pump for a selectable timeperiod, said control means controlling said shut off means to stop flowthrough said transfer conduit when said circulation pump is operating,said treatment conduit having an inlet for withdrawing waste water fromsaid waste water treatment tank, said treatment conduit having an exitfor returning water to said treatment tank and said exit is locatedadjacent the bottom of said treatment tank, said system furthercomprising an air pump, for delivery of gas under pressure to said ozonegenerator.
 14. The system of claim 13 wherein said system furthercomprises a black water collection tank, and said system furthercomprising a second transfer conduit for transferring at least a portionof said contents from said black water collection tank to said wastewater collection tank.